#define F_CPU 20000000UL  // 20 MHz CPU clock

#include <stdlib.h>
#include <avr/io.h>
//#include <avr/interrupt.h>
#include <util/delay.h>



int main(void) 
{
	
	DDRD |= _BV(PD7); // set led pin to output
	
	PORTD |= _BV(PD7); // led on, pin high
	//PORTD &= ~_BV(PD7); //led off, pin low
	//PINB |= _BV(0);
         
        while (1)                       /* loop forever */
        {
                /* set PC0 on PORTC (digital high) and delay for 500mS */
                PORTD &= ~_BV(PD7);                
                _delay_ms(500);
                
                /*  PC0 on PORTC (digital 0) and delay for 500mS */
                PORTD |= _BV(PD7);
                _delay_ms(500);
        }
	
	
	return 0;
}